Design Of Continuous Wave Doppler Fuze’s Anti-frequency Sweeping Jamming Method Based On Sample Entropy

The battlefield environment radio fuze faced is becoming more and more complex,which poses great threat to the effective work of radio fuze.CW(Continuous Wave)Doppler Fuze is widely used in conventional ammunition weapon system,but the theoretical analysis and experimental results show that it is very difficult for the fuze to resist the interference of frequency sweep jamming.In order to improve the anti-jamming performance of CW Doppler Fuze,this paper presents a design of anti-jamming method based on multi-scale entropy,using different entropy characteristics of demodulated output signals of autodyne transceiver under different signals to distinguish the target signals and the jamming signals.This can improve the anti-frequency sweeping jamming capability of CW Doppler Fuze effectively.The thesis first theoretically analyzed and simulated the state of autodyne transceiver of fuze under different signals,and clarified the different state of autodyne transceiver under different signals,which was reflected in the demodulated output signal of autodyne transceiver.This established the theoretical basis of using entropy algorithm in feature extraction of demodulated output signal of CW Doppler Fuze.By analyzing the characteristics of demodulated output signals of autodyne transceiver of fuze,entropy was chosen as the characteristic parameter to distinguish the target signals and jamming signals.Computational complexity of different entropy algorithm was analyzed,as well as their performance of feature extraction in both time domain and frequency domain.The feasibility of sample entropy algorithm in feature extraction of demodulated output signals of fuze in both time domain and frequency domain was verified by experiments.In the end,the influence of noise on time-domain and frequency-domain entropy algorithm was compared.By improving the criterion of parameter choosing of multi-scale entropy,a method based on multi-scale entropy in frequency domain is designed.Monte Carlo experiments about accurate rate of classification shows that,under low SNR,this method still keeps a high detection rate of target signals and jamming signals,which makes it valuable in engineering application.